1.Field of the Invention
The present invention relates to a structural component made of organic matrix fiber composite, for use notably in the aeronautical field.
2.Description of the Related Art
The use of fiber-reinforced composites has been developed in the aeronautical field because such materials allow the production of components that are even more lightweight than can be achieved using metallic materials and allow the structures obtained from assembling such components to be simplified; in particular, the number of components can thus be reduced. The components are obtained for example by laying up laps of fibers preimpregnated with resin then by curing these or alternatively by producing a preform using dry fibers which are then impregnated with resin inside a mold in which a vacuum is created and into which the resin is injected at low pressure.
The present invention relates to the manufacture of components from at least in part dry fibers. The fibrous part is generally formed of small-diameter fibers bundled in rovings or strands. The fibers are, for example, made of carbon, glass or alternatively of a material such as aramid.
One way of producing structural components such as link rods which may or may not have a hollow body involves forming a fibrous structure by winding, weaving, knitting or braiding dry rovings along a mandrel the overall contour of which is that of the component that is to be obtained. The fibrous structure may be formed of one or a plurality of layers or may alternatively be of the three-dimensional type, depending on the properties, such as strength, desired. The assembly comprising the mandrel and the fibrous structure covering it is then impregnated with a resin which, after curing, forms a matrix incorporating the fibrous elements. The mandrel may be removed or eliminated from the preform obtained or alternatively may be left in situ if lightweight. The preform obtained may or may not thus be hollow, possibly of axisymmetric shape, of revolution or otherwise. It is then machined and, as appropriate, fitted with ancillary parts to form the definitive structural element.
If the component is to be assembled with other components to form a structure, then one or more longitudinal extension(s) of the wall of the body of the preform may be provided in order to create end fittings that form interfaces with the other elements of the structure into which the component is to be incorporated. Once the preform has been cured, the extensions are holed and possibly routed in order to obtain the end fittings. The formation of the holes in the end fitting may also be scheduled to take place at the start of manufacture.
The applicant company has already proposed a novel way of producing one or more end fitting(s) on a composite structural element. Patent application FR 2 893 532 describes a process for manufacturing an end fitting on such an element produced at least locally from a stack of primary plies of composite fibers.
The applicant company has now set its sights on a novel way of producing one or more end fitting(s) on a composite structural element produced by braiding a fibrous material onto a mandrel and impregnating the resultant preform with an organic resin.
U.S. Pat. No. 6,890,470 discloses a method of manufacturing a structural element made of fiber composite. A fibrous material in the form of rovings is applied in an automatic circular weaving operating to a double mandrel, possibly with pre-woven reinforcing layers incorporated between two layers; one of the mandrels is removed; the free woven part is then shaped into, for example, flanges, and everything is impregnated with resin using, for example, the known RTM technique and the second mandrel is then eliminated from the preform obtained. In an alternative form of embodiment, textile reinforcing elements are incorporated between the various layers of the weaving toward one longitudinal end of the preform. That end remains open and creates two extensions in the wall of the preform which extensions constitute interfaces to accept a member for connection to another structural component. This solution entails the production of a double end-fitting, or yoke from the wall of the preform.
U.S. Pat. No. 4,704,918 is known and relates to a force transmission rod comprising a longitudinal mandrel and reinforcing elements at the ends. The entire assembly is covered by a textile covering impregnated with resin. Pins positioned transversely in the reinforcing elements catch on the covering. The reinforcing elements end in a threaded hole directed along the axis of the rod so that a connecting member can be attached by screwing in.
A novel way of creating an interface with the structural component is proposed which improves the ability to withstand both compressive and tensile loading effectively in the connecting region while being simple to produce.